In a resealable plastic bag, combine the first four ingredients. Pound chicken to 1/2 inch thickness and cut into 1-1/2 inch pieces. Dip chicken pieces in butter. Place chicken pieces, a few at a time, into the bag and shake to coat. Heat oil in a skillet; cook chicken, turning frequently, until browned and juices run clear, about 6 to 8 minutes. To maintain chicken warm, put them in a baking pan at 300 °F; cover with aluminum foil.